An ordination of life histories using morphological proxies: capital vs. income breeding in insects

Abstract

Predictive classifications of life histories are essential for evolutionary ecology. While attempts to apply a single approach to all organisms may be overambitious, recent advances suggest that more narrow ordination schemes can be useful. However, these schemes mostly lack easily observable proxies of the position of a species on respective axes. It has been proposed that, in insects, the degree of capital (vs. income) breeding, reflecting the importance of adult feeding for reproduction, correlates with various ecological traits at the level of among-species comparison. We sought to prove these ideas via rigorous phylogenetic comparative analyses. We used experimentally derived life-history data for 57 species of European Geometridae (Lepidoptera), and an original phylogenetic reconstruction. The degree of capital breeding was estimated based on morphological proxies, including relative abdomen size of females. Applying Brownian-motion-based comparative analyses (with an original update to include error estimates), we demonstrated the associations between the degree of capital breeding and larval diet breadth, sexual size dimorphism, and reproductive season. Ornstein-Uhlenbeck model based phylogenetic analysis suggested a causal relationship between the degree of capital breeding and diet breadth. Our study indicates that the gradation from capital to income breeding is an informative axis to ordinate life-history strategies in flying insects which are affected by the fecundity vs. mobility trade off, with the availability of easy to record proxies contributing to its predictive power in practical contexts.

Day‐flying moths are smaller: evidence for ecological costs of being large

“…Male rather than female wingspan was used because females (but not males) of some moth species have reduced flight ability and disproportionately short wings (Snäll et al ., ). However, sexual size dimorphism in body mass is nonexistent to weak in Geometridae (Davis et al ., ).…”

Quantifying the effects of species traits on predation risk in nature: A comparative study of butterfly wing damage

“…We conducted phylogenetic comparative analyses to study correlations between wing damage parameters and species traits, as well as between intraspecific sex differences in wing damage parameters, foraging activity and body size. When SE was available for both damage parameters and species traits, we considered SE using a REML framework based on theory developed by Ives et al () implemented in R (Davis, Javoiš, Kaasik, Õunap, & Tammaru, ; Holm et al, ; R Core Team, ). This approach effectively gave more weight to species for which we had a higher sample size.…”

Weak and inconsistent associations between melanic darkness and fitness‐related traits in an insect

“…The indices of growth performance used should function as rather straightforward fitness correlates. Indeed, in capital breeding insects (Davis et al ., ), realized fecundity of females is largely determined by adult body mass, for which pupal mass is a reasonable proxy (Honěk, ; Tammaru et al ., , ; Rhainds et al ., ). Ematurga atomaria is clearly a capital breeder (Javoiš et al ., ) and shows a strong correlation between body size and fecundity (Meister et al ., ).…”